The present invention relates generally to medical devices, kits, and methods used in the treatment of vascular occlusions. More particularly, the invention relates to systems and procedures for crossing chronic occlusions in blood vessels with guidewires that may facilitate performance of subsequent treatment and therapies including angioplasty, atherectomy and stenting procedures.
Cardiovascular disease is a leading cause of mortality worldwide that can take on many different forms. A particularly troublesome form of cardiovascular disease results when a blood vessel becomes totally occluded with atheroma or plaque, referred to as a chronic total occlusion. Until recently, chronic total occlusions have usually been treated by performing a bypass procedure where an autologous or synthetic blood vessel is anastomotically attached to locations on the blood vessel upstream and downstream of the occlusion. While highly effective, such bypass procedures are quite traumatic to the patient. Recently, catheter-based intravascular procedures have been utilized to treat chronic total occlusions with increasing success. Catheter-based intravascular procedures include angioplasty, atherectomy, stenting, and the like, and are often preferred because they are much less traumatic to the patient. Before such catheter-based treatments can be performed, however, it is usually necessary to cross the occlusion with a guidewire to provide access for the interventional catheter. In some instances, crossing the occlusion with a guidewire can be accomplished simply by pushing the guidewire through the occlusion. The guidewire remains in the blood vessel lumen and provides the desired access path. In many cases, however, the guidewire inadvertently penetrates into the subintimal space between the intimal layer and the adventitial layer of the blood vessel as it attempts to cross the occlusion. Once in the subintimal space, it is very difficult and impossible in many instances to direct the guidewire back into the blood vessel lumen. In such cases, it will usually be impossible to perform the catheter-based intervention and other procedures may have to be employed that are relatively more traumatic. Catheters and methods for forming lateral penetrations through tissue to and from blood vessels past total occlusions are described in U.S. Pat. Nos. 5,443,497; 5,429,144; 5,409,019; 5,287,861; WO 97/13463; and WO 97/13471. Catheters having side guidewire entry ports spaced proximally from their distal tips are also described in U.S. Pat. Nos. 5,464,395; 5,413,581; 5,190,528; 5,183,470; 4,947,864; and 4,405,314. These and a variety of other specific interventional and pharmaceutical treatments have been devised over the years with varying levels of success for different applications.
The present invention provides methods and apparatus for crossing substantial or total occlusions in blood vessels. It is an object of the invention to traverse vascular occlusions or other blockages formed within blood vessels in order to provide pathways for the placement of guidewires or other interventional devices as part of an overall effort to restore or provide adequate circulation. It is advantageous to cross a substantially occluded blood vessel by finding and/or creating a path with the least or relatively low resistance through or around at least a portion of the occlusion which may include travel along or between the layers of a blood vessel wall in regions such as the subintimal space. The invention further provides methods, kits, and apparatus which facilitate crossing a chronic total occlusion in a blood vessel with a guidewire. In particular, catheters, guides, or other apparatus provided herein may be used with conventional or specialized guidewires to direct or redirect the guidewires from a subintimal space, or other areas between the different layers of a blood vessel wall, back into the blood vessel lumen. The disclosed apparatus include devices formed with relatively simple construction, and may be used in a relatively straight-forward manner.
One aspect of the invention provides apparatus for crossing a vascular occlusion by directing a lead device such as a guidewire around at a least a portion of the obstruction within the blood vessel wall. A deflecting catheter may controllably deflect or direct the guidewire through or around a vascular occlusion formed within the natural lumen of the vessel, and may direct the guidewire within a region in between the various layers of the vessel wall to completely or partially circumvent the blockage. The deflecting catheter may provide any combination of these controllable movements to position the guidewire in a manner that can facilitate interventional treatments such as stenting. Another variation of the invention includes a guidewire deflection system comprising a catheter body formed with at least one lumen extending along its length, a nosecone formed at the distal end of the catheter body having a distal and a lateral opening. The region surrounding the lateral opening may include an adjacent inclined surface. The distal opening and the lateral opening are both in communication with the catheter body lumen. In addition, a cannula may be included having a cannula port in communication with at least one passageway extending through at least a distal portion of the cannula. The distal end of the cannula may be configured to communicate with the inclined surface adjacent to the lateral opening to deflect the cannula away from the longitudinal axis of the catheter body. The distal portion of the cannula may further have a pre-formed shape resilient curve, and may be slidably positioned within the lumen of the catheter body. The distal portion may have a relatively axially aligned configuration with the lumen when the cannula is positioned within the catheter body, and a relatively curved configuration with the lumen when the cannula travels along the inclined surface and through the lateral opening of the catheter body when the cannula is distally advanced through the lumen within the catheter body. The guidewire deflection system may further comprise a guidewire configured to pass through the passageway of the cannula. A variety of imaging components or markers may be also positioned on various portions of the wire, cannula or catheter body. A hub assembly rotationally secured to the proximal end of the catheter body may be selected to controllably rotate the cannula and the catheter body.
In yet another embodiment of the invention, an intravascular catheter is provided having a catheter shaft formed with at least one longitudinal lumen. A nosecone may be positioned at the distal end of the catheter shaft having a first port in communication with the longitudinal lumen formed with a first cross-sectional area, and a second port in communication with the longitudinal lumen formed with a second cross-sectional area, wherein the first cross-sectional area is relatively larger than the second cross-sectional area. A cannula may be slidably positioned within at least a portion of the longitudinal lumen of the catheter shaft, and may be configured for passage through the first port which is relatively larger, but not through the second port of the nosecone which is relatively smaller in size. A guidewire may be also slidably positioned within at least a portion of the cannula passageway, and may be configured for passage through an inclined surface formed adjacent to the second port. The nosecone may further include imaging components or radiopaque markers that provide directional orientation.
Another embodiment of the invention provides a redirectable intravascular guidewire catheter. The catheter may be formed with a catheter shaft and a guidewire deflector formed at the distal end of the catheter shaft. The guidewire deflector may be formed as a nosecone assembly having a distal end port, a lateral port, and a relatively internal or external flapper assembly with a deflectable extension. The deflectable extension of the flapper assembly may have a first position that directs a guidewire tip through the distal end port when the guidewire tip is positioned relatively distal to the deflectable extension. It may further have a second position that directs the guidewire tip through the lateral port when the tip is positioned relatively proximal to the deflectable extension and advanced thereafter in a relatively distal direction. Additionally, a guidewire may be included in the catheter that is slidably positioned within the lumen of the catheter shaft. A portion of the flapper assembly may be also formed of a fluoroscopic material to provide an orientation marker for directional placement of a guidewire.
A redirectable guidewire catheter is further provided in accordance with the concepts of the invention comprising a catheter shaft, an actuator wire, and guidewire. The catheter shaft may be formed with a first lumen and a second lumen each extending along the catheter shaft respectively to a first distal opening and a second distal opening. The actuator wire may be slidably positioned with the first lumen of the catheter shaft, wherein the actuator wire is formed with a preformed distal end to provide an actuated position that is biased towards the second distal opening when advanced relatively distal through the first distal opening. Furthermore, the actuator wire may extend only within or beyond the outer surface of the catheter shaft at a relatively distal or distal most end portion of the catheter shaft. The guidewire may be slidably positioned within the second lumen of the catheter shaft, and may be deflected when advanced relatively distal through the second distal opening when the actuator wire is placed in its actuated position. In another variation of the invention, the redirectable guidewire catheter may have a catheter shaft with a first lumen and a second lumen each extending along the catheter shaft. A nosecone may be formed at the distal portion of the catheter shaft, wherein the nosecone includes a distal orifice and an interior region formed with a tapered surface. The actuator wire may be formed with a distal tip that is slidably positioned with the first lumen of the catheter shaft, wherein the distal tip of the actuator wire is redirected substantially away from the longitudinal axis of the catheter shaft when advanced relatively distal along the tapered surface of the nosecone and through the nosecone orifice. The guidewire may be slidably positioned within the second lumen of the catheter shaft, and may be deflected away from the longitudinal axis of the catheter shaft by contacting the redirected actuator wire when the guidewire is advanced relatively distal through the distal orifice.
Yet another variation of the invention provides an intravascular catheter for selectively deflecting a guidewire that includes a catheter body formed with a distal end and a longitudinal lumen formed along at least a portion of the catheter body. A support tube may be formed with a distal tube end that includes a cut-out portion to accept the distal portion of a cannula. The support tube may be slidably and rotatably positioned within the longitudinal lumen of the catheter body. The cannula may include at least one passageway extending through at least a distal end portion of the cannula, wherein the distal portion of the cannula has a pre-formed shape resilient curve that may communicate with the cut-out portion when the cannula is slidably positioned within the conduit of the support tube. The proximal tube end of the support tube may be connected to a rotating assembly to rotate the support tube relative to the catheter body. Another variation of the intravascular catheter may include a support tube connected to the distal cannula end, wherein the support tube is formed with a distal tube end section, a proximal tube end section, and a backbone connecting the distal and the proximal tube end sections. The support tube or the distal cannula end may be preformed with a predetermined shape to deflect the distal cannula end away from the longitudinal axis of the catheter body when the distal cannula end is extended proximally past the distal end of the catheter body.
Another aspect of the invention provides methods for crossing a substantially occluded blood vessel. The method may include the steps of selecting a guidewire with a deflectable distal tip configured for placement in a blood vessel wall, creating a longitudinal dissection plane within the blood vessel wall by inserting the guidewire into blood vessel wall from within the blood vessel lumen at a proximal location relative to a vascular occlusion, forming a channel along the blood vessel wall by advancing the guidewire in a relatively distal direction along the blood vessel wall, and selectively deflecting the distal tip of the guidewire at a relatively distal location relative to the proximal location back into the blood vessel lumen. An interventional or diagnostic catheter may be advanced over the deflected guidewire from a position relatively proximal to the occlusion, through the channel, and back into the blood vessel lumen.
Other variations of the invention described herein also include methods where total occlusions are crossed by first forming a track or channel from a lumen in a blood vessel into a subintimal space between an intimal layer and an adventitial layer of the blood vessel. The track may be formed so that it extends from a location proximal of the total occlusion to a location which is relatively distal to the total occlusion, or at any positioned located therebetween. A passage may be then formed from the track back into the blood vessel lumen at the relatively distal location. In one variation of the invention, the track may be formed by advancing a wire through the blood vessel lumen into the subintimal space by typically advancing the wire until it encounters the total occlusion. By continuing to advance the wire in a generally distal direction, it may pass into the subintimal space of the blood vessel, and may be further advanced toward a desired distal location. After the wire is located or confirmed at a point relatively distal to the total occlusion or original point of insertion, it may be typically deflected from the track or channel back into the blood vessel lumen.
In some exemplary methods described herein, the wire may be deflected using a deflecting catheter. Typically, the deflecting catheter may be advanced over a proximal end of the wire and advanced into the track within the subintimal space. The wire and the deflecting catheter may be manipulated so that the wire is deflected laterally through the intimal layer back into the blood vessel lumen. Such deflecting catheters may be also useful in axially supporting the wire as it is advanced into and/or through the track, i.e. the catheter can enhance the xe2x80x9cpushabilityxe2x80x9d of the wire when it is advanced forward through any resisting material. Specific designs for such deflecting catheters are described in detail below. The wire, which is initially positioned within the track in the subintimal space, may be alternatively withdrawn through the deflecting catheter and exchanged for a second wire or device suitable for penetrating through the intimal layer of the blood vessel wall back into the lumen. It will be appreciated that the wires and/or deflecting and other catheters may be freely exchanged over or through one another in a conventional matter without departing from the scope of the invention.
Various imaging techniques may be used in accordance with the invention to determine where the wire and/or deflecting catheter are positioned with respect to a vascular occlusion so that the wire may be returned to the blood vessel lumen at a desired location or beyond the occlusion. For example, the position determination can be made by fluoroscopically imaging the blood vessel in a conventional manner. Alternatively or additionally to such fluoroscopic imaging, intravascular imaging, e.g. intravascular ultrasonic imaging (IVUS), and a variety of optical imaging modelities, such as optical coherence tomography (OCT), may be employed. For example, an ultrasonic imaging guidewire may be used to initially access the subintimal space and/or may be exchanged for the wire which is used to access the subintimal space. An imaging guidewire present in the subintimal space may readily detect the presence or absence of occluding material within the blood vessel lumen. The transition from detecting occluding material to the lack of the same is a strong indication that the position of the guidewire has advanced beyond the total occlusion. The wire may be deflected thereafter and returned towards the blood vessel lumen. After a passageway is formed from the track or channel back into the blood vessel lumen, and a wire is in place across the total occlusion, the wire may be used as a guidewire for positioning interventional and diagnostic catheters across the obstruction. Interventional catheters are often positioned across the total occlusion for treating the occlusion, and include devices such as angioplasty balloon catheters, rotational atherectomy catheters, directional atherectomy catheters, and stent-placement catheters.
Another aspect of the invention provides methods for crossing a vascular occlusion with a deflecting wire. The wire deflecting step may include deflecting a cannula from the subintimal space of a blood vessel wall back into the blood vessel lumen, and thereafter passing the wire through a path defined by the cannula, typically by a lumen within the cannula. The cannula may be advanced over the wire after the wire is disposed or advanced within the subintimal space, and a cannula-deflecting step may be also included that involves distally advancing a resilient or preformed curved end portion of the cannula from a constraining lumen formed within a surrounding catheter or sheath back into the blood vessel lumen. Alternatively, a wire-deflecting step may comprise advancing a deflecting catheter over the wire which has been advanced into the subintimal space. A cannula may then be advanced through a lateral opening of the deflecting catheter, and penetrate through the intimal layer to define a path for the wire back into the blood vessel lumen. A wide variety of steerable and actively deployed cannulas may also be used in the foregoing applications.
The present invention further provides kits for crossing vascular occlusions comprising a wire-deflecting catheter having a lumen or mechanism capable of laterally deflecting a wire. The kit may further comprise instructions setting forth any of the methods described above. Other methods and apparatus formed in accordance with the invention, as specifically described herein, may be also combined to provide numerous kits for many applications as in the treatment of coronary artery and peripheral vascular occlusions. Optionally, the kits provided herein may further comprise a wire for penetrating into the subintimal space and/or back into the blood vessel lumen. The kit may still further comprise a package for containing a wire deflecting catheter, instructions for its use as described in the various methods herein described, and other optional devices including additional wire(s). Suitable packages include pouches, trays, tubes, boxes, and the like. The instructions may be printed on a separate package insert or may be printed in part or in whole on the packaging itself. The components of the kit within the package may be sterilized by conventional procedures.
Apparatus according to another aspect of the invention provides wire-deflection systems. Exemplary wire-deflection systems usually comprise a wire-deflecting catheter which includes a catheter body and a deflecting cannula. The catheter body has a proximal end, a distal end, and at least one lumen extending through at least a distal portion thereof. The lumen also has a distal opening and a lateral opening. In addition, the cannula has a proximal end, a distal end, and at least one lumen extending through a distal portion thereof. The distal portion of the cannula may also have a preformed, resilient curve. The cannula is slidably disposed within the lumen of the catheter body to assume (a) a straightened configuration when the cannula is proximally retracted within the catheter body lumen and (b) a curved configuration when the cannula is extended laterally through the lateral opening of the catheter body. In this way, the cannula can be selectively deflected through the intimal layer of the blood vessel back into the lumen of the blood vessel according to some of the preferable methods described herein. The system may further comprise a wire configured to pass through the cannula lumen. The wire may be a conventional guidewire or a modified wire having a sharpened distal tip intended particularly for penetrating the intimal layer of the blood vessel wall. Optionally, the wire may further comprise an imaging apparatus such as an ultrasonic imaging means. The catheter body may include a fluoroscopically visible marker near its distal end. The marker can be configured to permit visual determination of the rotational orientation of the distal end of the catheter body when viewed as a two-dimensional fluoroscopic image. The catheter body will usually be reinforced to enhance torsional rigidity, and may further comprise a distal nose cone wherein the distal and lateral openings are defined within the nose cone. The distal end of the cannula will usually be pre-formed in a smooth curve which may extend over an arc in the range from about 15 to 135 degrees, usually from about 45 to 90 degrees. The preformed curve may also have a radius in the range from approximately 0.5 mm to 15 mm, usually from approximately 2 mm to 10 mm. These and other objects and advantages of the invention will become more apparent upon further consideration of the entire specification and drawings. Additional aspects and details of the invention will become more apparent to those skilled in the relevant are upon review of the following detailed description of the invention set forth below.